Summary:
The middleware for automatically converting Systrace traces to HTML and popping the browser hasn't worked properly for a while, since the version on Homebrew generates some code that uses `Object.observe`, which was deleted from Chrome ages ago. People have complained about it, but fixing it properly has proven to be harder than expected, so I suggest we simply update the message with instructions for people to load it on Chrome, which is what all of us have been doing anyway (AFAIK).
Closes#12445
Reviewed By: javache
Differential Revision: D4700153
Pulled By: gaearon
fbshipit-source-id: 0c33099babed93b3c70d36ae9dfc7d82460c8269